A magnetic sensor is provided with a carrier that has a cavity shaped to receive a magnet in sliding association therein. Ribs are provided to guide the movement of the magnet into the cavity and a deformable rib is used to hold the magnet at a precise position determined by an active calibration process. A magnetically sensitive component is rigidly attached to a substrate and the substrate is rigidly attached to the carrier in which the cavity is formed. Electrically conductive leads are molded into the carrier and extend through the carrier to positions where they can be electrically connected to circuit runs on the substrate. A flexible wall can also be formed in the carrier to deflect in response to the insertion of a magnet into the cavity. This provides additional holding capability that retains the magnet in position when an external force is removed.